Boyle's Law states that the volume of a gas is inversely related to the pressure. Students will discover this relationship by graphing lab data, and will use this relationship in an equation to solve problems. In the previous lesson, students used data for Charles' law to discover the mathematical relationship between temperature and volume by graphing, both by hand and using a spreadsheet program. Following this lesson both laws will be incorporated in the Combined Gas Law and the Ideal Gas Law.

See standards for unit.

Use of format for lab write-up. Measuring and reading with graduated equipment. Reading a volume with a meniscus. Using the computer word processing and spreadsheet programs. Substitution into formulas for problem solving.

Set up for Boyle's Law lab - for each group: Clamp a meter stick to a ring stand on one side and a gas measuring tube, closed end up, on the other side. Using latex tubing, connect the gas measuring tube to a tube with both ends open. Add water into the open end of the second tube, trapping a sample of air in the gas measuring tube. (Work the water and air back and forth to do this). By raising and lowering the second tube the pressure can be varied and measured by the height on the meter stick. The air volume in the gas measuring tube will also vary, and the volume in milliliters can be read from the graduations on the tube. To get a larger range of readings, you may need to measure heights over a 2 meter range. Meter sticks may be taped to the wall starting at floor level, with the closed tube clamped on a table or lab counter. This allows for raising and lowering pressure from the starting point, and for larger differences in volume.

Group lab reports and graphs. Homework problems.

1. To prepare for this activity, students will need a data table listing pressure (to 1.00m) and volume (to 0.1 ml). (You may want them to add columns for 1/V and Px1/V). Students observe demonstrations of Boyle's law: squeezing a balloon or observing a balloon grow larger under the bell jar of a vacuum pump when the vacuum is turned on. 2. In lab groups, students manipulate apparatus, recording at least 10 pressures and volumes. Students calculate 1/V and P x 1/V. 3. Each lab group enters data using a computer spreadsheet program, and prepares graphs of P vs V and P vs 1/V. (Lab groups can also use the computer word processing program to produce a complete lab write up according to format provided by the teacher.) 4. After sharing graphs and observing that the P vs 1/V produces the straightest line and P x 1/V produces a reasonably constant product, the teacher introduces the formula P1 x V1 = P2 x V2. Students observe examples of problems and complete practice problems for homework.

One computer for each group with a word processing and spread sheet program. Lab apparatus as described. Calculators.